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Top 5 Tips for High Performance Mortars

Video Transcript

Every day, tile and natural stone are being installed in and under conditions that are just too challenging for your average tile setting materials. Think of exterior applications exposed to freeze/thaw cycles, submerged assemblies and suspended slabs subject to deflection.
One of the keys to installing tile effectively is understanding the vital role of high performance mortars.

Tip #1: For improved performance, install tile with an ANSI A118.15 mortar
The first American National Standard to address the characteristics of latex or polymer modified mortars was A118.4. Due to the wide variation in performance within this standard, the Tile Council of North America adopted a new standard in 2012. ANSI A118.15 differentiates higher performance, polymer-modified mortars and recommends them for more demanding applications. The new standard describes these products as “improved”, modified, dry-set, cement mortars. Mortars meeting A118.15 are designed to increase adhesion, reduce water absorption, and provide greater bond strength, along with resistance to shock and impact.
This standard is especially relevant given current tile trends, such as heavy and large format tile, gauged thin porcelain panels, and the increasing use of larger glass tile. ANSI A118.15 improved mortars should always be specified and used when demanding tile materials or project conditions require increased bond strength or other high performance attributes.

Tip #2: Understand the role of shear bond strength
Much higher shear bond strength is the biggest single difference between A118.4 and A118.15 mortars. For example, in the improved standard, the requirement is doubled for a 28-day shear bond to impervious tile such as Porcelain.
This standard recognizes mortars that exhibit increased bond strength with vitreous, hard to bond tile in demanding situations and under extreme conditions.
The shear test is conducted by bonding two tiles together, then forcing them apart along the same plane until the mortar fails.
This action represents the most common failure mode where stress shears tiles from the substrate. The lab testing identifies the maximum shear stress that the mortar can withstand as recorded in pounds per sq inch or PSI.
Many A118.15 mortars are appropriate for applications requiring enhanced flexibility, such as exterior or above ground installations. CUSTOM’s Crack Prevention mortars are ideal for these conditions, even protecting against small in-plane cracks in the substrate that can cause cracks in the tile or grout. When mortars meet more rigorous requirements, they qualify for categories designating their additional attributes indicating where these products should be specified.

Tip #3: Use an appropriate mortar for large and heavy tile
In 2016, ANSI and the TCNA added an H designation to the A118.15 standard to recognize those mortars meeting the requirements for today’s popular large and heavy tile. Mortars displaying the H designation must pass repeated test cycles that assess shrinkage and durability, even when applied to a half inch thickness. CUSTOM’s H rated mortars exceed the standard, and are formulated for application up to ¾” without slumping. These mortars help prevent common issues caused when large format tiles are warped or domed and require mortar buildup.

Tip #4: When tiling walls and ceilings…think of a T
Walls are being tiled everywhere you look, including many building exteriors. Particularly when using large and heavy tiles*, it’s critical to use a mortar that will not allow the tile to slip from its position. ANSI mortars that pass the test for non-sag are designated with a T, which stands for thixotropic. This term refers to the mortar’s ability to lock the tile in place on a vertical surface, rather than sagging or slipping down the wall. Thixotropic mortars should be used on walls and ceilings where tile installations need to defy gravity.

Tip #5: Obey the speed limits of your mortar
The letter designations for the remaining mortar attributes are easy to remember. F stands for fast setting and E means extended open time. To qualify as a fast setting mortar, the material must achieve 50 psi shear strength within 4 hours. CUSTOM has several fast setting mortars that exceed the standard. These mortars allow grouting within 2-3 hours, making them ideal for fast-track projects. Each of these products also meets the requirements for non-sag, heavy tile, or both. CUSTOM’s extended set mortars allow 50% more working time over a standard mortar for setting tile in hot or windy conditions.

ANSI A118.15 adds important options for architects and contractors who need to achieve specific performance requirements. This standard makes it easier to specify the right mortar for the job and reduce the possibility of failures due to the selection of a lower performance mortar.

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